Cardiac rehabilitation programs (CRP) reduce cardiovascular mortality in patients with myocardial infarction, angina and after coronary revascularization. Modifiable coronary risk factors such as physical inactivity, overweight and high serum lipid levels improve after CRPs. However, only 30% of patients currently enroll in CRPs and attrition may reach 60%. Barriers include older age, female gender, lack of social support, high co-pays, distance, depression and fear or dislike for certain types of exercise. Clearly, there is a need to develop programs tailored to the characteristics and needs of those who do not attend presently available programs. Tai Chi, a mind-body intervention based on light/moderate aerobic exercise accompanied by meditative components, improves aerobic capacity in older sedentary adults, as well as exercise self-efficacy, quality of life and mood in patients with heart failure. In addition, Tai Chi may overcome multiple barriers to traditional CRP. Tai Chi can be practiced safely by elderly and deconditioned individuals; it does not require any particular equipment and it may be performed at any time and place, thus fostering adherence. Since Tai Chi is usually taught in groups, and is safe even in high-risk patients, it has been successfully offered in community centers thus overcoming transportation barriers and limiting costs. Our long-term goal is conduct a phase III randomized clinical trial (RCT) to determine the efficacy of Tai Chi in improving overall physical activity in patients with recent coronary events or procedures that are unable or unwilling to attend traditional CRPs. The overall objectives of this treatment development study are to define the content, optimal dose, feasibility and safety of a Tai Chi intervention in this population; and to refine the design of th future RCT. Specifically, we will use an iterative modified Delphi technique to adapt the protocol and materials of an existing Tai Chi intervention for patients with heart failure to our specific study population (aim 1) and to select the optimal control group(s) for the future RCT (aim 2). After a preliminary pre-pilot testing of the acceptability of the Tai Chi intervention in a small (n=10) group of patients (aim 3), 60 patients (30 per dose) will be randomized to a standard dose or to a high dose of the intervention (aim 4). We will estimate the feasibility and safety f each dose and obtain estimates of effect size on changes from baseline physical activity (assessed with accelerometers) and on the proportion of patients achieving current recommendation for physical activity. Additional outcomes will be body weight, quality of life, mood, and perceived social support. Measurements will be conducted at baseline, 3-, 6-, and 12 months after enrollment. Based on findings from aim 4, the investigative team will make the final adjustments to the Tai Chi intervention protocol (aim 5). Data generated from the proposed study will lead to the design of a phase III RCT to assess the efficacy of Tai Chi in promoting physical activity in patients with recent coronary events or procedures that are unable or unwilling to attend traditional CRPs.